User:Mav/Introduction to GIS notes by maveric149

Introduction to GIS Notes by maveric149. Please use these notes in any way allowable by the w:GNU FDL. However, you might want to drop me a line in my talk page after you make a wikipedia article from this information, so that I don't make a similar article from the same data. I also plan on somehow marking the text in this file that has already been incorperated into wikipedia.

Characteristics: Used to show air-route distances. Distortion-free at Azimuthal point (which is the central point on the map). Distortion increases as you move away from central point. Other examples of Azimuthal projections; Lambert Equal Area, Oblique Aspect Orthographic, North Pole Stereographic

Albers Equal Area Conic projection

Characteristics: Distorts scale/distance everywhere except along standard parallels, Used for large nations that extend more in east / west directions than North / South. Distortion-free at standard meridians. Anything off of standard meridian is distorted. Examples of other Conic projections are; Equidistant, Lambert Conformal, and Polyconic.

Longitudinal range of UTM zone 23Equation to find Western Boundary

180-[(n-1) x 6o] = xo

Equation with 23 for n

180-[(23-1) x 6o] = 48o

Equation to find Eastern Boundary

180-(n x 6o) = xo

Equation with 23 for n

180-[(23-1) x 6o] = 42o

Range is therefore:

42o West to 48o West

UTM Zone Questions
Number of w:meters wide for any UTM Zone at the equator (at the equator, every degree w:longitude is 111.11 kilometers)

111.1 kilometers/degree x 6o = 666.666 kilometers

666.666 km x 1000 m/km = 666,666 meters

Point on UTM Zone with easting of 400,000 meters. Grid declination is what?

West

Point on UTM Zone with easting of 560,000 meters. Grid declination is what?

East

NAD27 & 83 Questions
Use of quad map to measure the difference between w:NAD27 and w:NAD83 projections. How do you find the amount of shifting between these two?

In lower left corner of map states that the shift is shown by dashed corner ticks. You measure the shift with a ruler, and use the scale on the map to find the actual distance.